1. Field of the Invention
The invention relates to methods of producing slow-release pharmaceutical forms.
2. Discussion of the Background
A variety of alternative methods for producing slow-release pharmaceutical forms have already been described in a number of patents. For example:
The active principles may be diluted in an inert pulverulent excipient mixture, to which a surfactant is added (French Patent Nos. 82-13 613 and 82-04 672);
The principle of a matrix of a film may be employed. This matrix may or may not be embedded in an outer material or coated (Belgian Patent No. 783,661; French Patent Nos. 82-18 407, 82-21 109, 79-28 056, 76-30 362, and 72-19 993);
The active principles may be embedded in spherules or particles of a phospholipid (French Patent No. 76-02 016);
Complexes based on an ion exchange resin are employed, without being embedded or coated (Belgian Patent No. 876,857; European Patent No. 80 870 032.2; British Patent Nos. 1,576,016, 982,150, and 824,337; and French Patent No. 72-30 623);
The complex between the resin and the medicament may be treated with a solvating agent, and is provided with a water-permeable coating which forms a diffusion barrier (French Patent No. 77-35 611; U.S. Pat. No. 3,138,525; and British Patent No. 1,218,102).
All these inventions are principally concerned with galenic solid forms. Slow-release forms which involve liquid homogeneous forms are rare.